For certain applications (e.g., ELINT Radar) it is necessary to detect the phase transitions in a PSK signal and, more particularly, to detect (and count) the phase transitions or chips in a low level PSK signal in the presence of strong (or stronger) CW signals. Attempts have been made to use phaselock loops for this purpose. Phaselock loops, however, usually take milliseconds to lock onto an unknown carrier, while the PSK signals of interest generally last only for microseconds with chip durations of only nanoseconds. Also, phaselock loops do not operate satisfactorily in the presence of multiple, interfering, signals.